Bridge Scour Assessment Using Curvature of Horizontally Displaced Mode Shapes

Abstract

The ability to ensure the resiliency and to predict the future performance of coastal bridges is very dependent on identifying damages in critical components of the bridge rapidly after an event. Traditional vibration-based damage detection efforts focused mainly on the detection of fatigue cracking. Although detecting fatigue cracking is important, it does not contribute significantly to the total number of bridge failures in the United States. A critical review of the up-to-date literature showed that hydraulic loading, including scour, is responsible for about 50% of failed bridges. To this end, the focus of current research is the development and evaluation of damage features capable of rapidly identifying and quantifying the extent of deterioration of critical coastal bridge structures due to scour at submerged piers following extreme storm events without underwater instrumentations. This paper illustrates the use of the curvature of horizontally displaced mode shapes and introduces a Modified Curvature Damage Factor in which the difference in curvature of all significant mode shapes can be summarized by a single quantity to study the effect of scour on the dynamic response of the structure.